When is killing bacteria bad for us?

~1940-1960 was the “Golden Age” of antibacterial drug discovery. Every major class of antibiotics was discovered in those two decades. However, since the 1960s, few drugs have been developed to target new classes of bacterial targets. Rather, new drugs since the “Golden Age” are often chemical modifications of pre-existing antibiotics. Medicinal chemists engineered those modifications to existing drugs in order to avoid the resistance mechanisms that had evolved in the bacteria. In fact, one could group most all antibiotics in use today as hitting just four classes of bacterial targets [Walsh, C.T., Antibiotics (2003) ASM Press (below)]. Partly because antibiotics interfere with only a small class of targets in bacterial systems, overuse or misuse of antibiotics can lead to a troubling, rapid incidence of antibiotic resistance.

However, antibiotic resistance isn’t the only troubling outcome of antibiotic overuse. Dr. Martin Blaser of NYU wrote an eye-opening commentary in Nature last year on the dangers of accidentally killing too many of our beneficial bacteria with antibiotics, and suggestions for what precautionary measures we can take.

Here are some examples of how bacteria in our bodies help us:

Bacteroides species live in our colon and make our vitamin K

Bacteria in our gut guard us from harmful invading organisms

H. pylori help regulate the hormones ghrelin and leptin, which send hunger and satiety signals to regulate our eating habits.

One sign that overuse of antibiotics perturb the benefits that our bacteria provide us is illustrated by the correlation below:

What ideas do you have for how we can begin to tackle problems associated with antibiotic overuse?